Chairs are commonly used in the construction industry for the support of post-tension cables, rebars, and mesh above a surface. Typically, when such materials are used, they must be supported above the surface when the concrete is poured. Chairs are used with poured decks, precast work, and slab-on-grade applications. In normal use, a receiving area formed on the chair will contact and support the rebar while the base of the chair rests on a deck or on a grade. When the concrete is poured, the chair will support the post-tension cable or rebar a proper distance above the bottom surface.
In deck applications, the most common chair that is employed is a metal chair manufactured by Meadow Steel Products of Tampa, Fla. This chair is made from a pair of bent wires. A first bent wire has a receiving area for the receipt of the rebar. The receiving area is bent into the wire so as to form a generally parabolic indentation. The ends of the wire are bent at a ninety degree angle so as to support the wire in an upright condition above the deck. A second wire is formed in an inverted U-shaped configuration and is welded to the bottom edge of the receiving area of the first wire. The second wire also has ends that are bent at generally ninety degree angles. The first wire will extend in a plane transverse to the second wire such that the first and second wire form the "legs" of the chair. The ends of each of these wires will rest on the deck while the table is supported. After the concrete has solidified, and the deck is removed, the bottom surfaces of the ends of the wire will be exposed. As such, it is necessary to coat the ends of the wires with an anti-rust material. The rebar can be tied to the receiving area.
In normal applications, this Meadow Steel Products' chair will support a single rebar above the deck for a desired distance. However, in other applications, it is often desirable to place a second smaller chair beneath the larger chair so that another additional rebar can be extended so as to intersect with the first rebar. The chairs come in a large number of sizes and heights. In some circumstances, it is often desirable to place more than one rebar into the receiving area of the chair. To accommodate this problem the receiving area of the chair has a generally parabolic indentation.
Corrosion and cost are major problems affecting the Meadow Steel Products' chair. In order to form such a chair, a great deal of manufacturing must take place, including metal forming, bending, dipping, and welding. These activities, along with the cost of the material used to form the chair, make the cost of the chair relatively expensive. If the Meadow steel chair is not coated, then corrosion can adversely affect the product. Such corrosion can occur even in coated metal chains.
In the past, many attempts have been made to create chairs of plastic material that can serve the purposes of the Meadow Steel Products' chair. In general, such efforts have resulted in plastic chairs that are ineffective, cumbersome to use, or unable to withstand the forces imparted by the cable upon the chair. In some cases, support rings and other structures have been placed upon the plastic chairs so as to give the chair sufficient strength. Unfortunately, as such structures are added to the plastic chair, it becomes increasingly difficult to tie the rebar to the receiving area of the chair. This often requires a threading of the wire through the interior of the plastic chair in order to tie the rebar. As a result of this complicated procedure, many construction workers have been unwilling to use such plastic chairs. Additionally, the interior structures and support rings of such plastic chairs eliminate the ability to extend the rebars in an intersected relationship since one chair cannot be stacked upon or over another.
The plastic chairs of the past have often broken, collapsed, or tipped over in actual use. In the case of the plastic chairs, the base of the chair has only a small area of contact with the deck. Even with the necessary internal structure, experience has shown that such plastic chairs fail to withstand the weight of the rebar.
One particular type of plastic chair that has had some success is manufactured by Aztec Concrete Accessories, Inc. of Fontana, Calif. This chair has a plurality of legs that extend downwardly from a central receiving area. The central receiving area has a generally semi-circular configuration that can receive only a single rebar. An annular ring extends around the legs of the chair so as to provide the necessary structural support for the chair. The feet of the chair extend inwardly of the ring. In use, these chairs have had a tendency to tip over. Additionally, these chairs fail to accommodate the need to align rebars in an intersected relationship. The use of the annular ring extending around the legs of the chairs requires that a wire must be threaded through the interior of the chair in order to tie the rebar within the receiving area. As such, these chairs have been generally ineffective for meeting the needs of the construction industry. In the past, these and other plastic chairs have been unable to withstand the loads placed upon them. As such, breakage and insufficient rebar support has resulted.
It is an object of the present invention to provide a chair that is corrosion-proof and relatively inexpensive.
It is another object of the present invention to provide a chair that facilitates the ability to stack the chairs.
It is a further object of the present invention to provide a chair that withstands the forces imparted on it.
It is a further object of the present invention to provide a chair that is easy to manufacture and easy to use.
It is still another object of the present invention to provide a chair that has a receiving area that can accommodate several rebars.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.